The first thing I look for when tuning MySQL is delete queries that can be avoided. MySQL hates deletes. PG will let you do them, but you'll need to vacuum periodically to recover the space. And that vacuuming can easily be done in off hours and is VERY MUCH less strenuous to the DB than the actual delete in MySQL.
PG deletes faster than MySQL very much a myth
The first thing I look for when tuning MySQL is delete queries that can be avoided. MySQL hates deletes. PG will let you do them, but you'll need to vacuum periodically to recover the space. And that vacuuming can easily be done in off hours and is VERY MUCH less strenuous to the DB than the actual delete in MySQL.